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// See the LICENSE file in the project root for more information
// 
// Licensed to the Apache Software Foundation (ASF) under one or more
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// this work for additional information regarding copyright ownership.
// The ASF licenses this file to you under the Apache License, Version 2.0
// (the "License"); you may not use this file except in compliance with
// the License. You may obtain a copy of the License at
// 
// http://www.apache.org/licenses/LICENSE-2.0
// 
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// 

using System;

using log4net;
using log4net.Core;
using log4net.Util;

namespace log4net.Filter
{
    /// <summary>Simple filter to match a string in the event's logger name.</summary>
    /// <remarks>
    /// <para>
    /// The works very similar to the <see cref="LevelMatchFilter"/>. It admits two 
    /// options <see cref="LoggerToMatch"/> and <see cref="AcceptOnMatch"/>. If the 
    /// <see cref="LoggingEvent.LoggerName"/> of the <see cref="LoggingEvent"/> starts 
    /// with the value of the <see cref="LoggerToMatch"/> option, then the 
    /// <see cref="Decide"/> method returns <see cref="FilterDecision.Accept"/> in 
    /// case the <see cref="AcceptOnMatch"/> option value is set to <c>true</c>, 
    /// if it is <c>false</c> then <see cref="FilterDecision.Deny"/> is returned.
    /// </para>
    /// </remarks>
    /// <author>Daniel Cazzulino</author>
    public class LoggerMatchFilter : FilterSkeleton
    {
        /// <summary>Flag to indicate the behavior when we have a match</summary>
        private bool m_acceptOnMatch = true;

        /// <summary>The logger name string to substring match against the event</summary>
        private string m_loggerToMatch;

        /// <summary>Default constructor</summary>
        public LoggerMatchFilter()
        {
        }

        /// <summary><see cref="FilterDecision.Accept"/> when matching <see cref="LoggerToMatch"/></summary>
        /// <remarks>
        /// <para>
        /// The <see cref="AcceptOnMatch"/> property is a flag that determines
        /// the behavior when a matching <see cref="Level"/> is found. If the
        /// flag is set to true then the filter will <see cref="FilterDecision.Accept"/> the 
        /// logging event, otherwise it will <see cref="FilterDecision.Deny"/> the event.
        /// </para>
        /// <para>
        /// The default is <c>true</c> i.e. to <see cref="FilterDecision.Accept"/> the event.
        /// </para>
        /// </remarks>
        public bool AcceptOnMatch
        {
            get { return this.m_acceptOnMatch; }
            set { this.m_acceptOnMatch = value; }
        }

        /// <summary>The <see cref="LoggingEvent.LoggerName"/> that the filter will match</summary>
        /// <remarks>
        /// <para>
        /// This filter will attempt to match this value against logger name in
        /// the following way. The match will be done against the beginning of the
        /// logger name (using <see cref="M:String.StartsWith(string)"/>). The match is
        /// case sensitive. If a match is found then
        /// the result depends on the value of <see cref="AcceptOnMatch"/>.
        /// </para>
        /// </remarks>
        public string LoggerToMatch
        {
            get { return this.m_loggerToMatch; }
            set { this.m_loggerToMatch = value; }
        }

        /// <summary>Check if this filter should allow the event to be logged</summary>
        /// <param name="loggingEvent">the event being logged</param>
        /// <returns>see remarks</returns>
        /// <remarks>
        /// <para>
        /// The rendered message is matched against the <see cref="LoggerToMatch"/>.
        /// If the <see cref="LoggerToMatch"/> equals the beginning of 
        /// the incoming <see cref="LoggingEvent.LoggerName"/> (<see cref="M:String.StartsWith(string)"/>)
        /// then a match will have occurred. If no match occurs
        /// this function will return <see cref="FilterDecision.Neutral"/>
        /// allowing other filters to check the event. If a match occurs then
        /// the value of <see cref="AcceptOnMatch"/> is checked. If it is
        /// true then <see cref="FilterDecision.Accept"/> is returned otherwise
        /// <see cref="FilterDecision.Deny"/> is returned.
        /// </para>
        /// </remarks>
        public override FilterDecision Decide(LoggingEvent loggingEvent) 
        {
            if (loggingEvent == null)
            {
                throw new ArgumentNullException("loggingEvent");
            }

            // Check if we have been setup to filter
            if ((this.m_loggerToMatch != null && this.m_loggerToMatch.Length != 0) && 
                loggingEvent.LoggerName.StartsWith(this.m_loggerToMatch))
            {
                // we've got a match
                if (this.m_acceptOnMatch) 
                {
                    return FilterDecision.Accept;
                } 
                return FilterDecision.Deny;
            }
            else
            {
                // We cannot filter so allow the filter chain
                // to continue processing
                return FilterDecision.Neutral;
            }
        }
    }
}
